Gravimetric Moisture Testing Apparatus for Porous Materials
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Solution Overview
Problem
Current methods for determining moisture transport and storage properties in porous building materials are inadequate, as they require lengthy and costly testing, involve destructive techniques, and fail to characterize all transfer segments from dry to saturated states, especially under non-isothermal conditions, due to the complexity of moisture transport mechanisms involving phase changes and combined heat and moisture transport.
Innovation Solution
A test apparatus with a housing, framework structure, and air-conditioning system that allows for dynamic measurement of moisture transport and storage properties, featuring a sample holder with suspension arms to minimize axial stresses, and a control system for regulating humidity and temperature, enabling off-centre gravimetric measurements and automated data collection across the entire moisture range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If non-destructive measurement techniques based on neutron beam attenuation and nuclear magnetic resonance are used to determine moisture diffusivity, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex physical measurement systems (neutron beam attenuation, nuclear magnetic resonance) with a simple gravimetric measurement system. The apparatus uses basic weight measurement to determine moisture content, eliminating the need for sophisticated and expensive test equipment while achieving accurate moisture diffusivity determination through mathematical modeling of the drying process.
2Measurement precision
If traditional testing techniques are used to determine moisture transport properties, then measurement accuracy is maintained, but testing time becomes extremely long and costly
Solution Approach 1:
The patent implements continuous measurement of moisture content during the drying process rather than discrete stepped measurements. The gravimetric system continuously tracks weight loss, providing a complete moisture content vs. time profile. This continuous data collection enables more efficient determination of diffusion coefficients through curve fitting, significantly reducing testing time while maintaining accuracy.
Solution Approach 2:
The apparatus preconditions samples to a standard initial moisture content before testing begins. This preliminary saturation ensures that all samples start from the same known state, allowing for consistent and comparable results across different materials and testing conditions, thereby reducing the total time required to achieve statistically representative data.
3Reliability
If a large number of samples are tested to ensure statistical representativeness, then reliability of results is improved, but the number of usable samples decreases due to destructive techniques
Solution Approach 1:
The gravimetric measurement system is non-destructive, allowing samples to be reused after testing. The same sample can undergo multiple drying cycles and be tested repeatedly, generating multiple data sets from a single sample. This eliminates the need to consume multiple samples for statistical validation, preserving material resources while ensuring result reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This apparatus reduces testing time, allows for isothermal continuous dynamic testing without external intervention, and provides accurate diffusion coefficients for both vapor and liquid phases, suitable for the hygroscopic and capillary regimes, enhancing the understanding of moisture transport in building materials.
Implementation Method 1
a humidifying system for humidifying air inside the main chamber so as to obtain humidified air inside the main chamber
Implementation Method 2
a thermal regulation system intended for establishing the predetermined working temperatures of the humidified air inside the main chamber
Implementation Method 3
a humidified air recirculation system providing for a recirculation of the thermally conditioned humidified air inside the main chamber
Implementation Method 4
The support elements are suspended on suspension arms so as to keep the sample bar axially suspended in a horizontal plane without causing axial stresses in the bar
Implementation Method 5
The second suspension arm is connected to a force gauge (dynamometer) arranged in the main chamber, and the lower support elements are suspended on the suspension arms such that they keep the sample bar axially suspended
Data Source
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AI summary
The invention relates to a test apparatus comprising a housing (2) with an interior which forms a watertight main measuring chamber (3) for housing a bar (4), a framework structure (6) supporting the housing (2), a sample holder arranged in the main chamber (3), and an air-conditioning system for obtaining regulated relative humidity and temperature conditions for the air inside the main chamber (3). The apparatus also comprises a humidifying system, a thermal regulation system, and a humidified air recirculation system. The sample holder comprises first lower support elements (7) for supporting a first end part of the sample bar (4) and second lower support elements (8) for supporting a second end part of the sample bar (4) corresponding to the unsealed end face (4a) of the sample bar (4). A first suspension arm and a second suspension arm (9, 10) are each hinged at its lower end to one of the lower support elements (7, 8), the first suspension arm (9) being hinged to an upper part of the framework structure (6), and the second suspension arm (10) being hinged such that it is connected to a force gauge (15) arranged in the main chamber (3), the lower support elements (7, 8) being suspended on the suspension arms (9, 10) such that they keep the sample bar (4) axially suspended in a horizontal plane without causing axial stresses in the bar (4).